Deadlocking latch construction



Dec. 3, 1968 F. J. RUSSELL 3,414,307

DEADLOCKING LATCH CONSTRUCTION Filed March 13, 1967 INVENTOR.

l i F250 J. RUSSELL United States Patent 3,414,307 DEADLOCKING LATCH CONSTRUCTION Fred J. Russell, 8635 Otis St., South Gate, Calif. 90281 Filed Mar. 13, 1967, Ser. No. 622,628 4 Claims. (CL 292-2) ABSTRACT OF THE DISCLOSURE This invention relates to the structure of a deadlocking bar and face plate. The deadlocking bar has an end portion of enlarged diameter adapted to be received in a complementary recess in a faceplate when the door upon which it is mounted is in the closed position.

The invention has reference to door locks, but more particularly that part of a door lock commonly referred to as a deadlocking latch, the purpose of which is to provide a latch bolt which cannot be pried back when the door is in closed position. Only the deadlocking latch construction is involved in this patent application. The internal mechanism, which determines what is accomplished by the deadlocking latch, is a conventional and well known construction.

As shown in FIGURE 1, when the door is opened, both the large latch bolt and the relatively smaller deadlocking bar are in extended positions. When the door is swung to a closed position, the latch bolt strikes against the curved lip of a strike plate in the door frame and is cammed temporarily to a retracted position, carrying the deadlocking bar with it. After the latch bolt coincides with an opening in the strike plate, the latch bolt then reciprocates to extended position to hold the door in closed position. The deadlocking bar, however, is so positioned that it overlies a flat portion of the strike plate and is held by the strike plate in retracted position. By appropriate mechanism, forming no part of the present invention, the latch bolt is blocked against pryback when the deadlocking bar is in retracted position, and said latch bolt thus cannot be priced back by unauthorized means to a release position in order to open the door. The latch bolt then can only be retracted in conventional fashion by either knob action or key action. Once retracted as described and the door is again swung to open position, both the latch bolt and the deadlocking bar are extended again, as shown in FIGURE 1, and the conventional mechanism is then such that the latch bolt can be readily depressed, as it has to be when the door is being closed.

The combination of latch bolt and deadlocking bar in general, wherein there is a deadlocking bar of relatively small size in sliding relationship to a conventional latch bolt, is a long established practice. For this combination to be certain of operating at all times, the hole in the strike plate must be small enough so the dead bolt can never enter the hole, but large enough so the latch bolt can easily enter the hole. What often happens is that doors become warped, or perhaps the frame may become Warped, and What was originally a good Working adjustment for the parts becomes a poor adjustment, due to such warpings. Because there frequently has to be a rather comfortable clearance between the inside edges of the hole in the strike plate and the latch bolt, warping sometimes shifts the parts out of adjustment far enough so that the deadlocking bar of conventional construction slips into the hole in the srike plate when the door is in closed position. Then said deadlocking bar no longer is effective in preventing the latch bolt from being pried back.

It is therefore among the objects of the invention to 3,414,307 Patented Dec. 3, 1968 provide a new and improved combination of deadlocking bar and latch bolt, wherein the contacting outer end of the deadlocking bar is made enough larger so that it will continue to overlap and engage the strike plate despite warping of the door, without there being need to make the dead bolt itself any larger.

Another object of the invention is to provide a new and improved deadlocking bar and latch bolt combination, wherein the deadlocking bar has a special, larger head. Said larger head serves to prevent the deadlocking bar from entering the hole in the strike plate, yet said larger head can be depressed to a position which is flush with the edge of the door when both the latch bolt and the deadlocking bar are depressed simultaneously.

With these and other objects in view, the invention consists of the construction, arrangement, and combination of the various parts of the device, whereby the objects contemplated are attained, as hereinafter set forth, pointed out in the appended claims, and illustrated in the accompanying drawings.

In these drawings:

FIGURE 1 is an end perspective view of a fragment of door, showing the combination lock device mounted therein in operative position;

FIGURE 2 is a transverse sectional view of the fragment of door and an adjacent fragment of door frame, showing the position of parts when the door is closed;

FIGURE 3 is a longitudinal view of the lock device itself;

FIGURE 4 is an end elevational view showing the lock device mounted in a door; and

FIGURE 5 is an end elevational view, partially in section, taken on the line 55 of FIGURE 3.

In an embodiment of the invention which has been chosen primarily for the purpose of illustration, there is shown a fragment of door 10 in which a latch bolt and deadlocking bar combination, indicated generally by the reference character 11, has been mounted. A pocket 12 is provided in the door 10 for reception of the combination 11. The door 10 and the combination 11 mounted thereon are shown in FIGURE 2 in cooperation with a strike plate 13 mounted in a door frame 14.

The door 10 has opposite side faces 15 and 16 and a flat or moderately bevelled edge 17. The strike plate 13 has a strike lip 18, an exposed surface 19, and a hole 20 therein. A stop 21 is provided on the frame 14, against which the side face 16 is adapted to abut when the door 10 is in the closed position shown in FIGURE 2.

The latch bolt and deadlocking bar combination 11 reciprocates in a housing 25 to which is attached a faceplate 26 by means of screws 27 extending into appropriate flanges 28 at the adjacent end of the housing 25. Within the housing 25' is a reciprocatably mounted latch bolt 29 which has a bevelled end 30, a flat rear face 31, and a tailpiece 32 protruding from the right-hand end of the housing 25, as viewed in FIGURE 3.

Immediately adjacent the latch bolt 29 is a deadlocking bar 33 consisting of a shaft 34 and head 35. As best seen in FIGURE 3, it will be noted that the shaft 34 is semicircular in cross-sectional shape, as is also the head 35, but that the radius of the head 35 is substantially larger than the radius of the shaft 34. This accordingly provides a substantial overhang 36, as shown advantageously in FIGURE 3.

In the faceplate 26 is a relatively large hole 37 into which the latch bolt 29 extends. Immediately adjacent to said face plate 26 is a guide shim 40. This guide shim 40 preferably is made of a low friction material, such as a synthetic plastic resin material. In said guide shim 40 is a smaller hole 38 through which the shaft 34 of the deadlocking bar 33 extends. The holes 37, 38 are im- 3 mediately adjacent to and communicate with each other. These holes 37, 38 extend through the flanges 28 and into the interior of the housing 25.

Concentric with the small hole 38 is a recess 39 of relatively larger radius than the small hole 38. The recess 39, however, need extend only through the faceplate 26 and not through the flanges 28 located rearwardly. The recess 39 is made large enough to comfortably accommodate the head 35. Moreover, when the thickness of the head 35 is made to a dimension corresponding to the thickness of the faceplate 26, it will be clear that the head 35 will enter the recess 39, and its outside end will be flush with the outer surface of the faceplate 26, when the deadlocking bar 33 is fully depressed.

In operation, when the door is in the open position shown in FIGURE 1, the mechanism of the latch bolt and deadlocking bar combination 11 is such that both of these bolts extend outwardly to fully extended positions. In these positions, the outer end of the outer face of the head 35 is substantially flush with the outermost portion of the bevelled end 30 of the latch bolt 29. Should the latch bolt 29 be depressed, the mechanism is such that it carries the deadlocking bar 33 with it to depressed position. Such a movement occurs when the door 10 is swung to closed position with respect to the frame 14 and the stop 21. As the bevelled end 30 hits the strike lip 18 of the strike plate 13, the latch bolt 29 is depressed, carrying with it the deadlocking bar 33. When the door finally hits the stop 21, the latch bolt 29 will be in alignment with the hole 20 in the strike plate 13 and the mechanism of the dead bolt and deadlocking bar combination 11 is such that the latch bolt 29 will again be pushed out to extended position. In this relationship of parts, however, the head 35 of the deadlocking bar 33 will overlie the exposed surface 19 of the strike plate 13 and cannot extend. This is as it should be, because when the deadlocking bar 33 is prevented from being extended by appropriate conventional mechanism, it would not be possible to pry back the latch bolt 29, as for example, by unauthorized means such as a shim, and thereby force the door 10 open by unauthorized means. The head 35, moreover, is of diameter sufliciently large so that even if the door 10 were warped, or the door stop 21 were pushed out of place slightly, there would still be a portion of the head 35 overlying the ex posed surface 19 of the strike plate 13 to keep the deadlocking bar 33 in depressed position. If it were not for the presence of the head 35, the shaft 34 of the dead locking bar, 33 as small as it is, might inadvertently enter the hole 20 of the strike plate 13, along with the latch bolt 29.

Although in FIGURE 2 there is shown a relatively free fit, so that there is some measurable distance between the exposed surface 19 of the strike plate 13 and the adjacent flat edge 17 of the door 10, this space might be reduced to almost nothing, in which event the head 35 of the deadlocking bar 33 would recede into the recess 39 in the faceplate 26 and thereby avoid jamming.

When the latch bolt 29 is subsequently withdrawn by conventional means which act upon the tailpiece 32, the door 10 becomes unlatched, the latch bolt 29 clearing the hole 20 in the strike plate 13, at which time the door 10 can be swung open. Thereafter, the latch bolt 29 and the deadlocking bar 33 will reassume the positions shown in FIGURE 1.

While the invention has herein been shown and described in what is conceived to be a practical and satisfactorily operable embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is to be accorded the full scope of the claims, so as to embrace any and all equivalent devices.

Having described the invention, what is claimed as new in support of Letters Patent is:

1. A door lock device for installation in a door at a free edge thereof, said device comprising a housing adapted to be set in said free edge, a latch bolt recipfree edge, a faceplate at an outside end of the housing adapted to be set in said free edge, a latch bolt reciprocatably mounted in said housing, a first hole in said faceplate for reception of said latch bolt in position wherein a head on said latch bolt extends therethrough, a deadlocking bar reciprocatably mounted in said housing adjacent said latch bolt, said deadlocking bar comprising a shaft and a head on the outside end of the shaft, a second hole in said faceplate adjacent said first hole reciprocatably receiving said deadlocking bar therein, said head having a cross-sectional shape with an area greater than the cross-sectional area of said shaft and extending transversely outwardly beyond the outside surface of said shaft, said faceplate having a recess extending around said second hole, said recess being complementary in shape and size to the cross-sectional shape and size of said head, whereby the outer face of the head is substantially flush with the outside surface of said faceplate when the deadlocking bar is in fully depressed position.

2. A door lock device according to claim 1, wherein said deadlocking bar has a flat side in sliding engagement with an adjacent flat side of said latch bolt and wherein said head extends outwardly beyond the shaft of said deadlocking bar on the side opposite the side adjacent said latch bolt.

3. A door lock device according to claim 1, wherein said shaft is semicircular in cross-sectional form and said head is also semicircular in cross-sectional form but of radius larger than the radius of said shaft.

4. A door lock device according to claim 1, wherein the thickness of said head is not substantially greater than the thickness of said faceplate.

References Cited UNITED STATES PATENTS 2,807,488 9/1957 Schlage 292-2 MARVIN A. CHAMPION, Primary Examiner.

J. R. MOSES, Assistant Examiner. 

